Microscopes help us see small objects typically less than 500 nm nm = nanometer = 1/1,000,000 mm size of a human egg size of a sharp pencil point
Dec 28, 2015
Microscopes
help us see small objects typically less than 500 nm
nm = nanometer = 1/1,000,000 mmsize of a human eggsize of a sharp pencil point
Magnification making an image appear larger than its actual
sizenot actually changing the size of the object
Magnification indicated by _____ X
i.e. an object that is 100X had been magnified 100 times
the bottom image is 1860X
Resolution
the ability to distinguish the details of an image
measure of the clarity of an image
Resolution
improved by adjusting the focus of a microscope
resolution capability of a microscope of may be determined by an object’s size and degree of detail
Resolution
often displayed as a distancea smaller distance means that a smaller object
can be viewed clearlya smaller distance means the microscope has
better resolution
Magnification and Resolution
Both high magnification and good resolution are necessary to see small objects clearly.
Types of Microscopes
1. Compound Light Microscopes
2. Electron Microscopes
1. Compound Light Microscopes (CLM)
compoundmore than 1
lightilluminating the object
for clarity
light passes through two lenses to produce an enlarged image of a specimen
1. Compound Light Microscopes (CLM)
What is the possible compounded magnification of these lenses?
magnification of an object observed using this microscope is the multiplication of the 2 (or more) lenses used to view the object
1. Compound Light Microscopes (CLM)
2. Electron Microscopes
microscopes shoot electrons at dead objects/specimens
as the electrons bounce back, the energy is recorded and translated into an image
2. Electron Microscopes must be
viewed in a vacuumvacuum
○ no airno living cells
can be viewed
2. Electron Microscopes
There are two types of Electron Microscopes1. Transmission electron microscope (TEM)
2. Scanning electron microscope (SEM)
Transmission Electron Microscope (TEM)
Form 2D images
TEM images are always in black and white.
with the help of computers scientists add color to make things easier to see
Transmission Electron Microscope (TEM)
An electron beam is directed at a slice of a specimen that has been stained with metal ions.
Some structures become more heavily stained than others. Those heavily stained areas absorb electrons and in the lightly stained areas the electrons pass through hitting a fluorescent screen and forming an image on the screen.
Transmission Electron Microscope (TEM)
Scanning Electron Microscope (SEM)
essentially works the same as a TEM (electron beams)
shows 3D images of the surface of a specimen
Scanning Electron Microscope(SEM)
Strain of Staphylococcus aureus bacteria (20,000x)
sample is coated with a very thin layer of metal
again, color has been added with a computer
Scanning Electron Microscope(SEM)
Comparing Magnificationand Resolution
Microscope Type
Magnification
Resolution
CLM 2,000 x 200 nmTEM 50,000,000 x 50 pmSEM 500,000 x 1 nm
(1 nm = 1,000 pm)nm = nanometer (1 nm =1 billionth of a meter)pm = picometer (1 pm = 1 trillionth of a meter)
Microscope Collage
See Microscope Collage rubric.
Other Resources to use:Textbook
○ Pages 50 – 54